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This invention relates to high performance mixed signal integrated circuit (IC) testing systems and, more particularly, to a mixed signal device under test (DUT) board interface adapted to provide high functionality by providing high quality and high density analog and digital testing and signal connections to the IC device being tested.
IC testing systems typically test ICs either before a die bearing the circuit is detached from a wafer or after the IC is packaged on a chip carrier. Depending upon the functionality of the IC, the IC testing system may require both analog and digital signal testing circuitry as well as different types of analog or digital circuitry. As used herein, mixed signal testing is intended to include not only hybrid analog and digital signal testing, but also combinations of different types of analog or digital signal testing, for example general purpose analog and high speed analog, audio and video, or digital and high speed digital signals). For example, digital audio and video ICs used in Compact Disc and video disc players process digital signals as well as generate analog signals used to produce the analog sounds or video images. As these components increase in functionality and become more complex, the IC testing systems required to test these components must increase, not just in signal testing density (i.e. the number of digital or analog circuits that can be tested) but also in the mix or diversity of signal types (i.e. digital signals, audio signals, video signals, radio frequency signals, power signals, power control signals, etc.) that can be tested.
In order to test an IC on a wafer, typically, the test electronics which include individual circuit testing modules, are mounted in a test head at one end of an articulated arm. The test head can accommodate a plurality of different types of circuit testing modules, including for example, digital circuit testing modules (also referred to as Digital Pin Electronics Cards) and analog circuit testing modules which can include audio, video and/or RF circuit testing instrumentation. Mounted on one surface of the test head is the device under test board or DUT board. The DUT board includes a printed circuit board or similar electronic interconnect board that receives signals from a DUT board interface and connects them to the appropriate points of the device under test (e.g. the IC) on the wafer. The DUT board is sized to fit into an opening in the wafer handler, generally less than 12 inches in diameter. Once the DUT board is positioned in the opening, the wafer handler moves the wafer in position to allow probe pins on the DUT board to contact the appropriate points of the IC on the wafer in order to allow testing of various circuit elements of the IC.
In order to test a packaged IC, a different type of DUT board is used. This type of DUT board includes a socket that is adapted to receive the packaged IC and make electrical contact with the leads of the package in order to connect the circuit testing modules to the IC. In this embodiment, a part handling device, such as a pick and place robotic manipulator, is used to pick up the packaged IC and position it in the socket to be tested. The test head and the DUT board remain stationary during this process.
In typical analog circuit testing applications, it is often necessary to provide signal conditioning circuitry between the digital or analog circuit testing modules and the IC. This signal conditioning circuitry is typically provided on a load board which is inserted in the signal path between the circuit testing module and the DUT board. One of the disadvantages of using a load board in mixed signal applications is that the length of the signal path between the circuit testing modules and the IC is increased and consequently, the digital signal testing performance is decreased. In addition, the space available for signal conditioning circuitry on the load board becomes limited as the analog and digital testing channel density increases.
Accordingly, it is an object of this invention to provide an improved mixed signal integrated circuit testing system.
It is another object of this invention to provide an improved mixed signal integrated circuit testing system adapted to provide high performance digital signal testing.
It is a further object of this invention to provide an improved mixed signal integrated circuit testing system adapted to provide high density analog and digital signal testing instrumentation.
It is a still further object of this invention to provide an improved mixed signal integrated circuit testing system adapted to provide high density analog and digital signal testing instrumentation and increased load board signal conditioning capacity.
It is a still further object of this invention to provide an improved mixed signal integrated circuit testing system adapted to provide high density mixed signal testing instrumentation which can provide substantially the short signal delays need to test one type of circuitry as well as provide a replaceable or reconfigurable system configuration module for providing different types of signal conditioning circuitry.
The present invention is directed to mixed signal circuit testing systems adapted for testing highly integrated circuits (ICs) which can include various types of high performance digital and analog circuitry. The analog circuit types can include, for example, audio, video, power, power control, and radio frequency. In accordance with the invention, the mixed signal circuit testing system is adapted to provide high signal testing channel density as well as high performance digital signal test functions and diverse analog signal testing functionality. The system is also adapted to conform to conventional physical size requirements for testing ICs on a wafer and thus can serve to replace prior art integrated circuit testing systems.
The testing function of a system in accordance with the invention is accomplished by removably connecting (such as by means of a socket or pin probes) at least a portion of the IC to an analog and/or digital test module. The test modules can include the signal generating and signal measuring instrumentation necessary to perform a broad range of analog or digital test functions
A mixed signal IC testing system in accordance with the present invention includes a system controller adapted for controlling a first type of circuit testing module and a second type of circuit testing module. The circuit testing modules are mounted in a test head and operatively coupled to the system controller. A DUT board provides a means for connecting the mixed signal IC testing system to the IC being tested. The DUT board is mounted to a DUT board interface adapter which defines the DUT board interface. The first type of circuit testing module is operatively connected to a first portion of a DUT board interface adaptor via a first interconnect coupling. The second type of circuit test module is operatively coupled to a second portion of the DUT board interface adapter via a system configuration module. The system configuration module is connected to the second portion of the DUT board interface adapter via a second interconnecting coupling and to the second type of circuit testing module via a third interconnect coupling. The system configuration module can be removable in order to provide the flexibility to test a wide range of circuit types as well as a varying mix of circuit types and configuration.
The DUT board interface adapter can include a first interface adapter element nested with a second interface adapter element. The first interface adapter element can be connected to the first type of circuit testing module and the second interface adapter element can be connected to the second type of circuit testing module. In one embodiment, the first interface adapter element can be connected exclusively to one type of circuit testing module, for example, the digital type circuit testing modules. In another embodiment, the first interface adapter element can be connected exclusively to one type of circuit testing module and the second interface adapter element can be connected exclusively to a different type of circuit testing module. The first interface adapter element can include a circular peripheral portion that is adapted to nest with a circular opening in the second interface adapter element. Alternatively, the first interface adapter element can include an annular ring and the second interface adapter element can include an annular ring that is adapted to nest concentrically with the first interface adapter element. In an alternative embodiment, the DUT board interface adapter can be mounted to the test head via a compliant coupling to permit the DUT board interface adapter to move slightly relative to the test head.
In accordance with the present invention, the mixed signal DUT board interface is supported by a test head that includes at least one of the first type of circuit testing module and at least one of the second type of circuit testing module. In one preferred embodiment, the first type of circuit testing module is a digital circuit testing module adapted for testing digital circuits and the second type of circuit testing module is an analog circuit testing module adapted for testing analog circuits. The mixed signal DUT board interface includes a first interface adapter element, adapted for engaging a DUT board, and for operatively coupling at least one of the digital circuit testing modules to the DUT board to permit high performance digital signal testing of an IC coupled to the DUT board. The digital circuit testing module or modules are connected to the DUT board interface adapter via the first interconnect coupling or the digital interconnect coupling. The mixed signal DUT board interface also includes an analog interconnect adapted for coupling at least one of the analog circuit testing modules to a system configuration module to permit analog testing signals to be transferred between the analog circuit testing modules and the system configuration module.
The mixed signal DUT board interface can further include a system configuration module operatively connected to the analog circuit testing module via the second interconnect coupling. The system configuration module can include a second DUT board interface adapter coupled to the system configuration module permitting analog test signals to be transferred between the second DUT board interface adapter and the analog circuit testing module. The system configuration module can be connected to the DUT board interface adapter via the second interconnect coupling and to the second type of signal testing module or modules via the third interconnect coupling. In one embodiment, the first DUT board interface adapter and the second DUT board interface adapter are disposed in a common plane. Alternatively, the first DUT board interface adapter and the second DUT board interface adapter can be adapted to provide an interface for the DUT board that is disposed in a common plane.
The system configuration module is adapted for interconnecting signal conditioning circuitry to condition the analog test signals transferred between the analog circuit testing module and the second DUT board interface adapter. The system configuration module can be disposed in the same common interface plane as first DUT board interface adapter and the second DUT board interface adapter. Alternatively, the system configuration module can be disposed in a plane that is spaced apart from the interface plane.
The interface is adapted to connect the analog and digital test signals to a DUT board which is adapted to connect the analog and digital test signals to an integrated circuit. The first interface adapter element can include a plurality of digital interface elements operatively coupled to a digital circuit test module and the second interface adapter element can include a plurality of analog interface elements operatively coupled to an analog circuit test module.
The DUT board can include a plurality of DUT interface elements adapted to engage a set of the digital interface elements to permit digital test signals to be transferred between the DUT board and the digital circuit testing module and to engage a set of the analog interface elements to permit analog test signals to be transferred between the DUT board and the analog circuit testing module
Alternatively, the interface can be adapted to connect two or more different types of digital (or analog) test signals to a DUT board which is adapted to connect a plurality of types of test signals to an integrated circuit. The first interface adapter element can directly connect the one type of digital (or analog) signal testing module to the DUT board and the second interface adapter element can connect a second type of digital (or analog respectively) signal testing module to the DUT board via the system configuration module, thereby providing any necessary signal conditioning or loading circuitry between the signal testing module and the DUT board.